On Mon, Mar 01, 2010 at 10:42:50AM +0900, KOSAKI Motohiro wrote: > > AFAICT, even in the worst case, the latter call-site is well below 4K. > > I have no idea of the tty one. > > afaik, tty_buffer_request_room() try to expand its buffer size for efficiency. but Its failure > doesn't cause any user visible failure. probably we can mark it as NOWARN. > > In worst case, maximum tty buffer size is 64K, it can make allocation failure easily. > > Alan, Can you please tell us your mention? > (Added Greg as current tty maintainer) For reasons that are not particularly clear to me, tty_buffer_alloc() is called far more frequently in 2.6.33 than in 2.6.24. I instrumented the function to print out the size of the buffers allocated, booted under qemu and would just "cat /bin/ls" to see what buffers were allocated. 2.6.33 allocates loads, including high-order allocations. 2.6.24 appeared to allocate once and keep silent. While there have been snags recently with respect to high-order allocation failures in recent kernels, this might be one of the cases where it's due to subsystems requesting high-order allocations more. Anyone familiar with tty that might make a guess as to why it allocates more aggressively? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>